Most human malignancies result from the accumulation of mutations which activate oncogenes and inactivate tumor-suppressor genes. For pancreatic cancer, a limited number of genetic alterations are known, but it is clear that many others remain to be discovered. In the past, technical problems impaired these genetic studies. We recently assembled a novel panel of over 100 human pancreatic cancers, expanded by propagation as xenografts in nude mice. This resource, for the first time, allows such questions to be efficiently answered. Recent developments of sophisticated technologies have also accelerated the genetic dissection of this tumor. Because the biologic characteristics of the tumor are tied to the underlying genetic changes, knowledge of these relationships should enable advances in the understanding and management of pancreatic cancer. We realize that some of the aims of this proposal are not directly translational. However, the RFA states, "Because basic research in pancreatic cancer has lagged behind that of the other major solid tumors, greater leeway is given for basic research studies on pancreatic cancer." Furthermore, our preliminary studies have identified key markers, including the alterations of the p16 gene and of the BRCA2 locus in pancreatic cancer, which already have seen clinical application in inherited forms of pancreatic and breast cancer. In preliminary studies, detailed allelotyping has identified candidate regions for suspected novel tumor-suppressor genes in pancreatic cancer. We confirmed the high rate of K-ras mutations (>90%), established a high race of p53 mutations (70%), identified the common inactivation of the p16 gene (>80%), cloned the tumor-suppressor DPC4 from a novel hotspot of homozygous deletion on 18q, and used the representational difference analysis to provide the fine localization of the BRCA 2 gene through our identification of a small homozygous deletion at the BRCA2 locus in a pancreatic cancer arising in a setting of familial breast cancer. Specifically, this project aims to continue this work to identify new tumor-suppressor genes, identify activated oncogenes, and use these genetic clues to understand the clinical settings in which pancreatic cancer arises and spreads.